Method for manufacturing a cover for an electronic package and electronic package comprising a cover

ABSTRACT

A cover for an electronic package is manufactured by placing an optical insert, having opposite faces and configured to allow light radiation to pass therethrough, between two opposite faces of a cavity of a mold in a position such that said optical faces of the optical insert make contact with said opposite faces of the cavity of the mold. A coating material is injected into the cavity and around the optical insert. The coating material is set to obtain a substrate that is overmolded around the optical insert so as to produce the cover. An electronic package includes an electronic chip mounted to a support substrate with the cover formed by the overmolded substrate mounted to the support substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional from U.S. patent application Ser. No.15/689,976 filed Aug. 29, 2017, which claims the priority benefit ofFrench Application for Patent No. 1750051, filed on Jan. 3, 2017, thedisclosures of which are hereby incorporated by reference in theirentireties.

TECHNICAL BACKGROUND

The present invention relates to the field of electronic packages, inparticular to those which comprise electronic chips including lightradiation emitters and/or light radiation sensors.

BACKGROUND

It is known practice to produce electronic packages which compriseelectronic chips provided with integrated optical elements, lightradiation sensors and/or emitters, mounted on carrier substrates andwhich comprise encapsulation covers for the chips, which covers aremounted on the carrier substrates. These covers are provided withoptical members, generally made of glass, which allow light to passthrough, which members are transferred onto the covers after the latterhave been mounted on carrier substrates and are fixed to the covers byway of layers of adhesive.

SUMMARY

According to one embodiment, a method is proposed for manufacturing atleast one encapsulation cover for an electronic package, comprising thefollowing steps: placing at least one optical insert, having oppositefaces and allowing light radiation to pass therethrough, between twoopposite faces of a cavity of a mold in a position such that said facesof the optical insert make contact with said faces of said cavity of themold; injecting a coating material into said cavity, around said opticalinsert; and setting the coating material in order to obtain a substratethat is overmolded around said optical insert, so as to produce at leastone cover comprising at least one optical insert and at least a portionof said overmolded substrate. The method may comprise a later step ofcutting through said overmolded substrate and at a distance from saidoptical insert.

The mold may comprise opposite layers made of a compressible material atleast partly forming said faces of said cavity, said opposite faces ofsaid optical insert bearing on these layers.

Said opposite faces of the mold may be parallel.

One of said faces of the cavity of the mold may comprise at least onezone surrounded by at least one groove, one of the faces of the opticalinsert making contact above this zone, such that said substrate of theobtained cover is provided with at least one protruding ribcorresponding to said groove of the mold.

The method may comprise a later cutting step carried out through saidprotruding rib.

One of said faces of the cavity of the mold may comprise at least twozones surrounded by at least one main protruding groove and separated byat least one intermediate groove, optical inserts having faces makingcontact above said zones, such that said substrate of the obtained coveris provided with at least one peripheral protruding rib corresponding tosaid main groove of the mold and at least one intermediate ribcorresponding to said intermediate groove of the mold.

The method may comprise a later cutting step carried out through saidmain protruding rib.

Said intermediate groove may have a shallower part, such that saidsubstrate of the obtained cover is provided with an intermediate ribhaving a notch corresponding to said intermediate groove of the mold.

An electronic package is also proposed which comprises: a carriersubstrate; at least one electronic chip having a back face fixed to afront mounting face of the carrier substrate and provided with at leastone optical element integrated within its front face; and anencapsulation cover of said chip, comprising a substrate that isovermolded around an optical insert allowing light radiation to passfrom one side of the overmolded substrate to the other, said cover beingfixed at least above said carrier substrate.

Said cover may be fixed above said carrier substrate by way of anannular bead of adhesive or an annular strip of adhesive, interposedbetween a peripheral zone of the carrier substrate and a peripheral zoneof said overmolded substrate.

Said overmolded substrate may be provided with a ring-shaped ribsurrounding said chip at a distance, the cover being fixed above saidcarrier substrate by way of a strip of adhesive interposed between saidcarrier substrate and said ring-shaped rib.

Said overmolded substrate may be provided with an intermediate ribdelimiting two chambers, this intermediate rib being fixed on top ofsaid carrier substrate by way of a strip of adhesive.

The carrier substrate may be provided with two electronic chips locatedin said chambers, respectively.

The carrier substrate may be provided with an electronic chip thatextends through a notch of said intermediate rib, this intermediate ribbeing fixed on said chip by way of a strip of adhesive.

Said electronic chip may be provided with two optical sensors located oneither side of said intermediate rib.

The carrier substrate may be provided with another electronic chipprovided with an optical transmitter.

Said overmolded substrate may be provided with two optical insertslocated on either side of said intermediate rib.

A cover for an electronic package is also proposed which comprises anoptical insert having opposite faces, made of a material that allowslight radiation to pass through from one face to the other, and asubstrate, made of an opaque coating material, overmolded around theinsert such that said opposite faces of the insert are at least partlyuncovered.

Said overmolded substrate may be provided, as a single part, with aring-shaped rib that surrounds at a distance from and protrudes withrespect to one of said opposite faces of said insert.

BRIEF DESCRIPTION OF THE DRAWINGS

Electronic packages and modes of manufacture of these packages will nowbe described by way of non-limiting examples, which are illustrated bythe appended drawings in which:

FIG. 1 shows a cross section of an electronic package;

FIG. 2 shows a cross section of a mold for manufacturing a cover for thepackage of FIG. 1, in one manufacturing step;

FIG. 3 shows a horizontal cross section of the mold of FIG. 2;

FIG. 4 shows a cross section of the manufacturing mold of FIG. 2, inanother manufacturing step;

FIG. 5 shows a step of manufacturing the package of FIG. 1, in crosssection;

FIG. 6 shows a cross section of another electronic package;

FIG. 7 shows a cross section of a mold for manufacturing a cover of thepackage of FIG. 6, along VII-VII as shown in FIG. 8, in onemanufacturing step;

FIG. 8 shows a horizontal cross section of the mold of FIG. 7;

FIG. 9 shows a cross section of a manufacturing mold along IX-IX of FIG.7;

FIG. 10 shows a cross section of the manufacturing mold of FIG. 7, inanother manufacturing step;

FIG. 11 shows a step of manufacturing the package of FIG. 6, in crosssection;

FIG. 12 shows a cross section of another electronic package;

FIG. 13 shows a cross section of the package of FIG. 12 along XIII-XIII;and

FIG. 14 shows a cross section of a mold for manufacturing the cover ofthe package of FIG. 12.

DETAILED DESCRIPTION

FIG. 1 illustrates an electronic package 1 which comprises a carriersubstrate 2, made of an opaque dielectric material, including anintegrated network of electrical connections 3 and having a back face 4and a front mounting face 5. The outline of the carrier substrate 2 is,for example, square or rectangular.

The package 1 comprises an electronic chip 6 mounted above the frontface 5 of the carrier substrate 2 by way of a layer of adhesive 7interposed between the front face 5 of the carrier substrate 2 and aback face 8 of the electronic chip 5.

The chip 6 is provided, in a front face 8, with an integrated opticalelement 9, such as a light radiation emitter and/or sensor.

The chip 6 is electrically connected to the connection network 2 by wayof electrical wires 10 connecting pads of the front face of the carriersubstrate 2 and front pads of the electrical connection network 2 formedon the front face of the chip 6, the back face 4 of the carriersubstrate 2 being provided with electrical connection pads for externalelectrical connections.

The package 1 comprises an encapsulation cover 11 which is located aboveand at a distance from the chip 6, parallel to the carrier substrate 2,and which has an outline corresponding to that of the carrier substrate2.

The cover 11 comprises a ring-shaped overmolded substrate 12 made of anopaque coating material, for example a thermosetting resin, which hasopposite back and front faces 13 and 14, which are flat and parallel,and comprises an optical insert 15 in the form of a disc and theperiphery of which is integrated and held within a through-passage 16 ofthe overmolded substrate 12. The optical insert 15 is made of a materialthat allows light radiation to pass through the substrate 11, from oneface to the other, and is located facing the integrated optical element9 of the chip 5. The optical insert 15 is, for example, made of glass,optionally optically treated glass, and has, for example, a square orrectangular outline. For example, the optical insert 15 has back andfront faces 17 and 18 which extend substantially in the plane of theback and front faces 13 and 14 of the overmolded substrate 11.

The cover 11 is fixed above the carrier substrate 2 by way of an opaquelocal ring-shaped connecting spacer 19 interposed between a peripheralzone of the front face 5 of the carrier substrate 2 and a peripheralzone of the back face 13 of the overmolded substrate 12 of the cover 11,the ring-shaped bead 19 extending at a distance from the periphery ofthe chip 6 and the electrical connection wires 10 and at a distance fromthe periphery of the optical insert 15 of the cover 11.

The thickness of the ring-shaped spacer 19 determines the gap betweenthe cover 10 and the carrier substrate 2. The ring-shaped spacer 19 maycomprise an opaque adhesive including spacing balls which determine aminimum gap between the cover 10 and the carrier substrate 2.

Thus, the carrier substrate 2, the cover 11 provided with the opticalinsert 15 and the connecting bead 19 define a sealed chamber 20 in whichthe chip 6 and the electrical connection wires 10 are located. If theintegrated optical element 9 of the chip 6 is a light radiation emitter,this light radiation is emitted outwards through the optical insert 15of the cover 11. If the integrated optical element 9 of the chip 6 is alight radiation sensor, external light radiation reaches the integratedoptical element 9 by passing through the optical insert 15 of the cover11.

The cover 11 is the result of a wafer-scale manufacturing process whichwill now be described.

As illustrated in FIGS. 2 and 3, a mold 120 is obtained which comprisesa lower part 21 and an upper part 22 between which a cavity 23 isformed. The parts 21 and 22 of the mold 120 have faces 24 and 25 whichare opposite, flat and parallel, and which delimit the cavity 23 in thedirection of the thickness of the covers 11 to be obtained. Optionally,these opposite faces 24 and 25 are covered with layers 26 and 27 made ofa compressible material.

A plurality of optical inserts 15 is also obtained, resulting forexample from cutting a substrate along parallel rows and parallelcolumns.

With the mold 120 open, optical inserts 15 are placed on thecompressible layer 26, at respective locations in the sites Ecorresponding to covers 11 to be obtained, these sites E being adjacentand arranged in a square or rectangular matrix.

Next, the mold 120 is closed by placing the upper part 22 above thelower part 21. In this position, the opposite faces 17 and 18 of theoptical inserts 15 are facing the opposite faces of the cavity 23 andare pressed against the compressible layers 26 and 27. Free spacesseparate the optical inserts 15, these spaces straddling the rows andcolumns separating the adjacent sites E.

Next, as illustrated in FIG. 4, an opaque coating material, for examplea thermosetting epoxy resin, is injected into the cavity 23 of the mold120 and this coating material is set.

A collective substrate 12A, provided with optical inserts 15 andovermolded around these optical inserts 15 while formingthrough-passages 16, is obtained.

According to one variant embodiment, the collective substrate 12A is cutalong the rows and columns delimiting the sites E in order to obtaincovers 11.

According to another variant embodiment, as illustrated in FIG. 5, anopaque collective carrier substrate 2A is obtained which is provided, atsites E corresponding to electronic packages 1 to be obtained, withrespective electronic connection networks 3 and which is provided, onits front face 5A, with electronic chips 6 at respective locations inthe sites E and with electrical connection wires 10, these sites E beingadjacent and arranged in a square or rectangular matrix.

Next, collective beads of opaque adhesive 19A are spread over the frontface 5A of the collective carrier substrate 2A, along border zonesbetween the sites E surrounding the central zones of the sites E inwhich the chips 6 are located, these collective beads 19A being intendedto form spacers 19 at each site E.

Next, the overmolded collective substrate 12A, provided with the opticalinserts 15, is placed on top of the beads of adhesive 19A and thesebeads of adhesive 19A are set so as to fix the collective substrate 12Aabove the collective carrier substrate 2A.

Next, the assembly formed is cut along rows and columns separating thesites E, perpendicularly to the substrates 2A and 12A and through thebeads of adhesive 19A, between and at a distance from the opticalinserts 15.

A plurality of electronic packages 1, produced at the sites E, is thenobtained, in each one of which the carrier substrate 2 is a portion ofthe collective carrier substrate 2A, the cover 11 comprises anovermolded substrate 12 formed by a portion of the overmolded collectivesubstrate 12A, including an optical insert 15, and the spacer 19 isformed by a portion of the collective beads of set adhesive 19A, thecover 11 resulting from the substrate 12 being overmolded around theoptical insert 15.

According to one variant embodiment, the beads of adhesive 19A could bereplaced by a grating made of a bonded rigid material, portions of thisgrating forming, after cutting, a spacer 19 at each site E.

FIG. 6 illustrates an electronic package 28, which differs from theelectronic package 1 as follows.

The electronic package 28 comprises a carrier substrate 29 including anintegrated network of electrical connections 30 and provided, on a frontface 31, with two electronic chips 32 and 33 which are remote from oneanother, the chips 32 and 33 being connected to the electricalconnection network 30 by electrical wires 34 and 35 and being providedwith integrated front optical elements 36 and 37.

The electronic package 28 comprises an encapsulation cover 38 whichcomprises an overmolded substrate 39 extending in front of and at adistance from the chips 45 and 46 and provided, as one piece, with aprotruding rear peripheral rib 40 and a rear inner rib 41, forming aninternal partition.

The overmolded substrate 39 has back surfaces 39 a and 39 b which arecircumscribed by the peripheral rib 40 and separated by the inner rib 41and has a flat front surface 39 c. The back surfaces 39 a and 39 b areparallel to the front surface 39 c. The rear ends of the rear peripheralrib 40 and of the inner rib 41 extend in one and the same plane which isparallel to the overmolded substrate 39.

The flat rear end of the rear peripheral rib 40 extends above aperipheral zone of the front face 31 of the carrier substrate 29, at adistance from the chips 32 and 33 and electrical wires 34 and 35. Theinner rib 41 passes between and at a distance from the chips 32 and 33.The flat rear end of the inner rib 41 extends above a medial zone of thefront face 31 of the carrier substrate 29 located between and at adistance from the chips 32 and 33.

The encapsulation cover 38 is fixed above the carrier substrate 29 byway of local strips of opaque adhesive 42 interposed between the rearends of the rear peripheral rib 40 and the inner rib 41 and the frontface 31 of the carrier substrate 29.

The cover 38 additionally comprises optical inserts 43 and 44, allowinglight to pass through, which inserts are integrated withinthrough-passages 45 and 46 of the overmolded substrate 39 and located oneither side of the intermediate rib 41 facing the optical elements 36and 37 of the chips 32 and 33. The optical inserts 43 and 44 extendbetween the surfaces 39 a and 39 b on the one hand and the surface 39 cof the overmolded substrate 39 on the other hand, respectively.

The carrier substrate 29 and the cover 38 delimit independent chambers47 and 48 separated by an inner rib 41 and in which the chips 32 and 33are located.

For example, the optical element 36 of the chip 32 may be a lightradiation emitter emitting light radiation outwards through the opticalinsert 43 of the cover 38 and the optical element 37 of the chip 33 maybe a light radiation sensor detecting external light radiation throughthe optical insert 44 of the cover 38. The electronic package 28 mayconstitute a means for detecting the proximity of a body by processingthe signals arising from the sensor 37.

The cover 38 is the result of a wafer-scale manufacturing process whichwill now be described.

As illustrated in FIGS. 7, 8 and 9, a mold 49 is obtained whichcomprises a lower part 50 and an upper part 51 between which a cavity 52is formed. The parts 50 and 51 of the mold 49 have opposite faces 53 and54 which delimit the cavity 23 in the direction of the thickness of thecovers 11 to be obtained.

The face 53 of the lower part 50 of the mold 49 has adjacent sites Earranged in a matrix, corresponding to covers 38 to be obtained. Theface 53 has cross-shaped main grooves 55 through the middles of whichpass the rows and columns of the matrix forming the sites E and, at eachsite E, an intermediate groove 56 that is parallel to the rows of thematrix and joins up with the grooves 55 located on either side of thesite E.

Thus, at each site E, the face 53 of the lower part 50 of the mold 49comprises flat zones 57 and 58 which are circumscribed by correspondingportions of the grooves 55 and separated by a corresponding intermediategroove 56. The flat zones 57 and 58 extend in one and the same plane.The grooves 55 and 56, which have a U-shaped cross section, have thesame depth with respect to the flat zones 57 and 58. According to onevariant embodiment, the flat zones 57 and 58 could extend in differentplanes.

The face 54 of the upper part 51 of the mold 49 is flat and parallel tothe zones 57 and 58 of the lower part 50 of the mold 49.

Optionally, the faces 57 and 58 of the lower part 50 of the mold 49 andthe face 54 of the upper part 51 of the mold 49 are covered with layers59, 60 and 61 made of a compressible material.

A plurality of optical inserts 43 and 44 is also obtained.

With the mold 49 open, optical inserts 43 and 44 are placed on thecompressible layers 59 and 60 of the lower part 50, at respectivelocations at the sites E corresponding to covers 38 to be obtained.

Next, the mold 49 is closed by placing the upper part 51 above the lowerpart 21, on the optical inserts 43 and 44. In this position, theopposite faces of the optical inserts 43 and 44 are pressed against thecompressible layers 59 and 60 on the one hand and against thecompressible layer 61 on the other hand.

Next, as illustrated in FIG. 10, an opaque coating material, for examplea thermosetting epoxy resin, is injected into the cavity 52 of the mold49 and this coating material is set.

A collective substrate 39A is obtained which is ribbed on one side atthe locations of the grooves 55 and 56 and provided with optical inserts43 and 44, which inserts are integrated and held within the coatingmaterial forming the collective substrate 39A, the latter beingovermolded around the optical inserts 43 and 44 while formingthrough-passages 45 and 46.

According to one variant embodiment, the collective substrate 39A is cutalong the rows and columns delimiting the sites E in order to obtaincovers 38.

According to another variant embodiment, as illustrated in FIG. 11, anopaque collective carrier substrate 29A is obtained which is provided,at sites E corresponding to electronic packages 1 to be obtained, withrespective electronic connection networks 30 and which is provided, onits front face 31A, with electronic chips 32 and 33 at respectivelocations at the adjacent sites E and with electrical wires 34 and 35.

Next, collective strips of opaque adhesive 42A are spread over the frontface 31A of the collective carrier substrate 29A at each site E with aview to forming the strips of adhesive 42 of the packages 28 to beobtained.

Next, the overmolded collective substrate 39A, provided with opticalinserts 15, is placed on top of the collective strips of adhesive 42A,and this adhesive 19A is set so as to fix the collective substrate 39Aabove the collective carrier substrate 29A.

Next, the assembly formed is cut along rows and columns separating thesites E, perpendicularly to the substrates 29A and 39A and through theribs 40A, in the direction of their length and dividing them in two inorder to form the rear peripheral rib 40, and through the correspondingstrips of hardened adhesive 42A.

A plurality of electronic packages 28, produced at the sites E, is thenobtained, the cover 38 resulting from the substrate 39 being overmoldedaround the optical inserts 43 and 44.

FIGS. 12 and 13 illustrate an electronic package 62 which differs fromthe electronic package 28 solely in the following arrangements.

In the same way as for the electronic package 28, the electronic package62 comprises an opaque carrier substrate 63 which is provided, on itsfront face 64, with two electronic chips 65 and 66 which are remote fromone another and bonded to the front face 64.

This time, the chip 65 comprises two front optical elements 67 and 68integrated within its front face 69 and the chip 66 comprises, as above,a front optical element 70 in its front face 71. The front opticalelements 67, 68 and 70 are aligned.

In the same way as for the electronic package 28, the electronic package62 comprises an encapsulation cover 72 which comprises an overmoldedopaque front substrate 73 provided with a protruding peripheral rear rib74 and a protruding rear inner rib 75, forming a partition.

This time, instead of being located between the chips 65 and 66, therear inner rib 75 straddles the chip 65, passing over the front face 69and between and at a distance from the front optical elements 67 and 68of the chip 65. For this purpose, the rear inner rib 75 has a notch 76through which the chip 65 passes.

The encapsulation cover 72 is fixed above the carrier substrate 63 byway of local strips of opaque adhesive 77 interposed between the frontface 64 of the carrier substrate 63 on the one hand and the flat rearends of the rear peripheral rib 74 and parts of the rear inner rib 75located on either side of the chip 65 on the other hand, and by way of alocal strip of opaque adhesive 78 interposed between the front face 64and the sides 79 and 80 of the chip 65 on the one hand and the flatfaces of the notch 76 of the inner rear rib 75 on the other hand.

The cover 72 additionally comprises optical inserts 81 and 82, allowinglight to pass through, which inserts are integrated withinthrough-passages 83 and 84 of the substrate 73 overmolded around opticalinserts 81 and 82. The optical inserts 81 and 82 are located on eitherside of the intermediate rib 75 and facing the optical element 67 of thechip 65 and facing the optical element 70 of the chip 66, respectively.

Thus, the carrier substrate 63 and the cover 72 delimit chambers 85 and86, separated by the inner rib 75, such that the optical element 67 ofthe chip 65 is located within the chamber 81 on the one hand, and theoptical element 68 of the chip 65 and the optical element 70 of the chip66 are located within the chamber 82 on the other hand.

According to one mode of operation, the optical elements 67 and 68 ofthe chip 65 are light radiation sensors and the optical element 70 ofthe chip 66 is a light radiation emitter. The emitter 70 of the chip 66emits light radiation outwards through the optical insert 82. This lightradiation present in the chamber 86 is detected by the sensor 68 of thechip 65. The sensor 67 of the chip 65 detects external light radiationthrough the optical insert 81. The electronic package 62 may constitutea means for detecting the proximity of a body by processing the signalsarising from the sensors 67 and 68.

The cover 72 is the result of a wafer-scale manufacturing processequivalent to that described above with reference to FIGS. 7 to 10.

For this purpose, as illustrated in FIG. 14, a mold 87 equivalent to themold 49 is obtained. The lower part 88 is provided with cross-shapedmain grooves 55 and intermediate grooves 56 which, this time, have arespective central part 90 which is shallower than the end parts 91 and92 located on either side of this central part, this central partallowing the notch 76 to be made.

The cover 72 is mounted on the carrier substrate in the same way as thatwhich has been described above with reference to FIG. 11.

However, before putting the cover 72 into place, a strip of adhesive inliquid or paste form is deposited on the chip 65, in order to form thelocal strip of opaque adhesive 78.

The invention claimed is:
 1. An electronic package, comprising: acarrier substrate; a first electronic chip having a back face fixed to afront mounting face of the carrier substrate and having a front faceincluding at least one integrated optical element; and an encapsulationcover over said first electronic chip, said encapsulation covercomprising a substrate that is overmolded around a first optical insertconfigured to allow light radiation to pass from one side of theovermolded substrate to another side of the overmolded substrate,wherein said overmolded substrate is provided with a ring-shaped ribsurrounding said first electronic chip at a distance, wherein saidencapsulation cover is fixed at least above said mounting face of saidcarrier substrate in a position such that the encapsulation coverextends above the first electronic chip, the encapsulation cover beingfixed above said carrier substrate by way of an adhesive mounting saidring-shaped rib.
 2. The package according to claim 1, wherein theadhesive is an annular bead of adhesive interposed between a peripheralzone of the carrier substrate and a peripheral zone of said overmoldedsubstrate.
 3. The package according to claim 1, wherein the adhesive isan annular strip of adhesive interposed between a peripheral zone of thecarrier substrate and a peripheral zone of said overmolded substrate. 4.The package according to claim 1, wherein said overmolded substrate isfurther provided with an intermediate rib delimiting two chambers, andwherein the adhesive is a strip of adhesive mounting said intermediaterib of the encapsulation cover above said carrier substrate.
 5. Thepackage according to claim 4, wherein said first electronic chip islocated within one of said two chambers and further comprising a secondelectronic chip located within another of said two chambers.
 6. Thepackage according to claim 4, wherein said first electronic chip extendsthrough a notch of said intermediate rib, and wherein the adhesive fixesthe intermediate rib on said first electronic chip.
 7. The packageaccording to claim 6, wherein said first electronic chip includes afirst optical sensor within one of said two chambers and a secondoptical sensor within another of said two chambers.
 8. The packageaccording to claim 7, further including a second electronic chipprovided with an optical transmitter within said another of said twochambers.
 9. The package according to claim 4, wherein said firstoptical insert is located on one side of said intermediate rib andfurther including a second optical insert located on another side ofsaid intermediate rib.
 10. The package according to claim 1, whereinopposite faces of the first optical insert are coplanar with one sideand another side of said overmolded substrate.
 11. The package accordingto claim 1, wherein said overmolded substrate is made of an opaquematerial.
 12. The package according to claim 1, wherein an outer surfaceof the ring-shaped rib is a cut surface.